This invention relates to compounds of Formula (I), wherein A is a carboaromatic or heteroaromatic ring having one or more substituents; R 6 Formula (A) is optionally substituted with one or more substituents; and n is 0, 1 or an integer greater than 1 and when n is 1 or greater the bond or bonds between the carbon atoms may be saturated or unsaturated, which bind the P2X 7 receptor with high affinity. This invention also relates to methods for the diagnosis, treatment or monitoring of disorders in which the P2X 7 receptor is implicated, in particular the diagnosis, treatment or monitoring of (the progression of) neuroinflammatory and neurodegenerative disorders in a subject.